Different sensitivity to streptolysin-O of cells in macrophage lineage

We have surveyed the sensitivity of cells in macrophage lineage to Streptolysin-O (SLO). SLO had cytotoxic activity on immature myeloid cell lines such as M1 and WEHI-3BD+. SLO was toxic to the cells after a 2-hr incubation. However, mature macrophage cell lines such as A640-BB-2, J774, and P388D1 were not sensitive to the same dose of SLO. After M1 cells were treated with leukemia inhibitory factor (LIF), a differentiation-inducer to macrophage, these cells became insensitive to SLO in one day. This cytotoxic action of SLO was inhibited by pretreatment with anti-Streptolysin-O antibody or cholesterol. These results indicate that SLO has different effects on macrophage lineage.